Liquid propellants are commonly known and used to generate thrust for rockets or other space vehicles. Propellant performance has been defined with regard to specific impulse and density; however, environmental impact and cost are now also factors in the selection of propellants.
Hydroxylammonium nitrate (“HAN”) has been considered as an alternative to hydrazine-based propellant because of its relatively low toxicity, higher energy density, higher specific impulse, and lower freezing point. For example, HAN is included in propellants as an oxidizer, along with a fuel and stabilizers.